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// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.
package markdown
import (
"fmt"
"strings"
)
var htmlEscaper = strings.NewReplacer(
`&`, "&",
`<`, "<",
`>`, ">",
`"`, """,
)
// RenderHTML produces HTML with the same behavior as the example renderer used in the CommonMark
// reference materials except for one slight difference: for brevity, no unnecessary whitespace is
// inserted between elements. The output is not defined by the CommonMark spec, and it exists
// primarily as an aid in testing.
func RenderHTML(markdown string) string {
return RenderBlockHTML(Parse(markdown))
}
func RenderBlockHTML(block Block, referenceDefinitions []*ReferenceDefinition) (result string) {
return renderBlockHTML(block, referenceDefinitions, false)
}
func renderBlockHTML(block Block, referenceDefinitions []*ReferenceDefinition, isTightList bool) (result string) {
switch v := block.(type) {
case *Document:
for _, block := range v.Children {
result += RenderBlockHTML(block, referenceDefinitions)
}
case *Paragraph:
if len(v.Text) == 0 {
return
}
if !isTightList {
result += "<p>"
}
for _, inline := range v.ParseInlines(referenceDefinitions) {
result += RenderInlineHTML(inline)
}
if !isTightList {
result += "</p>"
}
case *List:
if v.IsOrdered {
if v.OrderedStart != 1 {
result += fmt.Sprintf(`<ol start="%v">`, v.OrderedStart)
} else {
result += "<ol>"
}
} else {
result += "<ul>"
}
for _, block := range v.Children {
result += renderBlockHTML(block, referenceDefinitions, !v.IsLoose)
}
if v.IsOrdered {
result += "</ol>"
} else {
result += "</ul>"
}
case *ListItem:
result += "<li>"
for _, block := range v.Children {
result += renderBlockHTML(block, referenceDefinitions, isTightList)
}
result += "</li>"
case *BlockQuote:
result += "<blockquote>"
for _, block := range v.Children {
result += RenderBlockHTML(block, referenceDefinitions)
}
result += "</blockquote>"
case *FencedCode:
if info := v.Info(); info != "" {
language := strings.Fields(info)[0]
result += `<pre><code class="language-` + htmlEscaper.Replace(language) + `">`
} else {
result += "<pre><code>"
}
result += htmlEscaper.Replace(v.Code()) + "</code></pre>"
case *IndentedCode:
result += "<pre><code>" + htmlEscaper.Replace(v.Code()) + "</code></pre>"
default:
panic(fmt.Sprintf("missing case for type %T", v))
}
return
}
func escapeURL(url string) (result string) {
for i := 0; i < len(url); {
switch b := url[i]; b {
case ';', '/', '?', ':', '@', '&', '=', '+', '$', ',', '-', '_', '.', '!', '~', '*', '\'', '(', ')', '#':
result += string(b)
i++
default:
if b == '%' && i+2 < len(url) && isHexByte(url[i+1]) && isHexByte(url[i+2]) {
result += url[i : i+3]
i += 3
} else if (b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || (b >= '0' && b <= '9') {
result += string(b)
i++
} else {
result += fmt.Sprintf("%%%0X", b)
i++
}
}
}
return
}
func RenderInlineHTML(inline Inline) (result string) {
switch v := inline.(type) {
case *Text:
return htmlEscaper.Replace(v.Text)
case *HardLineBreak:
return "<br />"
case *SoftLineBreak:
return "\n"
case *CodeSpan:
return "<code>" + htmlEscaper.Replace(v.Code) + "</code>"
case *InlineImage:
result += `<img src="` + htmlEscaper.Replace(escapeURL(v.Destination())) + `" alt="` + htmlEscaper.Replace(renderImageAltText(v.Children)) + `"`
if title := v.Title(); title != "" {
result += ` title="` + htmlEscaper.Replace(title) + `"`
}
result += ` />`
case *ReferenceImage:
result += `<img src="` + htmlEscaper.Replace(escapeURL(v.Destination())) + `" alt="` + htmlEscaper.Replace(renderImageAltText(v.Children)) + `"`
if title := v.Title(); title != "" {
result += ` title="` + htmlEscaper.Replace(title) + `"`
}
result += ` />`
case *InlineLink:
result += `<a href="` + htmlEscaper.Replace(escapeURL(v.Destination())) + `"`
if title := v.Title(); title != "" {
result += ` title="` + htmlEscaper.Replace(title) + `"`
}
result += `>`
for _, inline := range v.Children {
result += RenderInlineHTML(inline)
}
result += "</a>"
case *ReferenceLink:
result += `<a href="` + htmlEscaper.Replace(escapeURL(v.Destination())) + `"`
if title := v.Title(); title != "" {
result += ` title="` + htmlEscaper.Replace(title) + `"`
}
result += `>`
for _, inline := range v.Children {
result += RenderInlineHTML(inline)
}
result += "</a>"
case *Autolink:
result += `<a href="` + htmlEscaper.Replace(escapeURL(v.Destination())) + `">`
for _, inline := range v.Children {
result += RenderInlineHTML(inline)
}
result += "</a>"
default:
panic(fmt.Sprintf("missing case for type %T", v))
}
return
}
func renderImageAltText(children []Inline) (result string) {
for _, inline := range children {
result += renderImageChildAltText(inline)
}
return
}
func renderImageChildAltText(inline Inline) (result string) {
switch v := inline.(type) {
case *Text:
return v.Text
case *InlineImage:
for _, inline := range v.Children {
result += renderImageChildAltText(inline)
}
case *InlineLink:
for _, inline := range v.Children {
result += renderImageChildAltText(inline)
}
}
return
}
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